We have lost something important and we have an unconscious urge to get it back. Laughter is an integral component of human happiness, and its absence is a pathology that is related to maladaptive and other dysfunctional behaviors (e.g. guilt, depression, worry)

Reasons why laughter is fast disappearing today include:

We live in a fast and stressful world. Very few things can make us laugh while hundreds can make us frown, howl and cry. The rapid growth of telecommunication has put the weight of the world's bad news onto everybody’s shoulders in almost real-time, resulting in extremely high fear levels. Death and destruction make headlines everyday, making everybody feel his/her own world is insecure. Guilt, doubt, worry and fear are powerful factors that induce stress, and stress is a silent body, mind & spirit killer.
Nobody wants to take responsibility. As a result, we as a society have become king escapists, refusing to take on the healthy yet hazardous path of learning from our own mistakes and growing in the present. Virtually all self-defeating behaviors are efforts at living in a moment other than the current one. “Now” is the only place where happiness and laughter can be experienced.

Guilt means that you use up your present moments being immobilized as a result of past event(s) which cannot be changed. It is by far the greatest waste of emotional energy because no amount of guilt can change history. It is a smoke screen that shifts the responsibility backward (for what you were or were not, did or did not do in the past) and provides an unhealthy reason to avoid the hard work of changing your path now: it is easier to immobilize yourself with guilt about the past rather than learn and grow in the present. Learning from our mistakes is a necessary part of our growth.

Worry is a clever device that keeps you immobilized in the now, about something in the future – frequently something over which you have no control. Like guilt, it is an excuse to avoid dealing with something in the now that threatens you or you are afraid of. Worrying keeps you from living by keeping you inactive. Its best antidote is action.

We live in a fear- and rule-based society. The whole world is full of serious people who believe that problems have to be approached carefully rather than lightly. It is commonly believed that if you laugh “you don't understand”, or “you are not a responsible person”. As a result we are not allowed to laugh, cry, be sad and we keep suppressing our emotions. The ensuing frustration, and often unhappiness, leads to stress and the whole list of diseases that come with it.
Three myths prevail about laughter:

You must have a sense of humor to laugh

You need to be happy to laugh

You need to have a reason to laugh

People have forgotten how to laugh. According to a study done by Dr. Michael Titze, a German Psychologist in the 1950's, people used to laugh 18 minutes a day, but today we laugh not more than 6 minutes per day, despite the huge rises in the standard of living. Children can laugh up to 300-400 times in a day, but when we grow into adults this frequency comes down dramatically to less than 15 times a day, if at all.

Sense of humor has become uncommon and uncertain. Due to excessive seriousness, the things at which we used to laugh heartily 50 years ago no longer stimulate even the faintest smile.

Happiness has become conditional on external factors. “Happiness” is primarily a mind phenomenon. The most common & accepted belief is that “If I get what I want, then I will be happy”. This naturally implies that if you don’t get “it” then you can’t be happy. Such forms of happiness never lasts long because of another human psychological phenomenon called “adaptation”. You get what you want, enjoy it (there is an initial high and you feel on top of the world), and in due time the happiness level comes down as you get used to the initial object of your desires. You are no longer excited about what you have. Then you start looking for something more, all kinds of sense pleasures, and the cycle starts again. Since human desires are endless and everything is temporary (we all have to die one day), true happiness never comes.

Laughter Yoga meets the need

Laughter Yoga is a simple technique that proved so powerful that it has become a worldwide grass-roots social movement (non religious, non sectarian, non political). It aims to promote world peace through laughter. It is based on the philosophy of “acting happiness” and is a physically-oriented technique, not a mental practice. In Laughter Yoga, you don't need to be happy, have a sense of humor, or even have a reason in order to laugh.

Laughter Yoga is commonly practiced in the context of Laughter Clubs, most of which are free and public. A typical Laughter Yoga session is a perfect blend of various stimulated laughter techniques, interspersed with gentle breathing and stretching exercises.

It is important to note that laughing as a form of exercise and of your own will is different from laughing with humor, at something. Humor is a left brain process that does not require participation and therefore involves no personal commitment. A lot of people are afraid of being vulnerable in silliness. This is why they prefer passive fun. When listening to a joke, there is no risk of looking or feeling silly and out of control. In contrast, laughing of your own will for no apparent reason forces you to leave the comfort zone of the known yet limited analytical brain and enter the unknown, ever new and ever changing world of the creative brain and experience its unlimited potential.

The worldwide success of Laughter Yoga can be explained with the following reasons:It is easy. Anybody can do it. Laughter Yoga crosses all barriers in that it is accessible and effective for most regardless of age, gender, race, physical condition, social status, etc. (some contra-indications do apply.)

The Laughter Yoga technique belongs to all and has no hidden agenda. Anybody / group can use it with equal benefit in any setting regardless of culture, religion, belief or political affiliation. We encourage all to be free and public.

It is socially and emotionally safe. Laughter Yoga makes competing and judging impossible: every laugh is successful. Laughter Clubs are the ideal platforms to laugh your way to silliness, because there is no fear of ridicule by anyone. As laughter opens us up and allows us to become vulnerable, we learn to trust and drop our defenses, becoming willing to make changes. We no longer need to keep score of the good things we do for others. We lose track, and we don't even care. Laughter makes us generous to a fault and we feel better giving than receiving.

No thinking required. There is sufficient data available from medical research to show that even if you pretend to laugh or act happy your body produces happiness chemicals. Our body-mind does not know the difference between thinking about doing something and actually doing it. Therefore, whatever may be the source of laughter it leads to the same set of physiological changes occurring in our bodies. Many actors and actresses all over the world have experienced the effect of faking emotions. Many times they felt sick after acting out sadness. This clearly indicates that if acting sad can make you sick, acting happy can make you healthy. The idea of Laughter Clubs is based on this philosophy of acting happiness. Another theory is “Motion Creates Emotion”. If you put your body into an act of happiness, your endocrine system will create the chemistry that goes with the behavior and directly impact your mood state, making you "feel" good regardless of what your analytical mind has to say.

Laughter is infectious. Self-induced, simulated laughter can easily be converted into real laughter when you do it in a group. Humans have a detector in their brain that is specifically devoted to laughter. This responds to laughter by triggering other neural circuits in the brain that generates more laughter. This explains why laughter is so contagious. Laughter spreads when you laugh in company and have good eye contact. We have all laughed without a reason when we were children. Children can laugh for no reason because they have very few inhibitions.

The very essence of laughing without a reason lies in developing your child-like spirit and playful attitude. If you can do that, laughter will come to you with great ease.

Laughter Yoga is a simple yet powerful form of aerobic exercise that makes you feel good. You don't need to sweat hard on the jogging tracks. According to Dr. William Fry, one minute of laughter is equal to 10 minutes on the rowing machine. Laughter exercise is suited for sedentary people and those who are confined to a bed or wheelchair. Fifteen minutes of laughter in the morning makes Laughter Club members feel fresh throughout the day. The reason for the sense of well-being is that you inhale more oxygen while laughing. Two thirds of the lung capacity comes from abdominal breathing, which means that if you don’t use your abdomen to breathe, approximately 2/3 of the air in your lungs is stale. Laughing repeatedly fully flushes the lungs to the full extent of their capacity, thereby bringing substantially more oxygen into the blood stream. It stands to reason therefore that as oxygen is the life line of the human body. The more you have, the better you feel.
Also:

Laughter makes it easier to cope with life and its challenges.

Laughter builds self-confidence

Laughter is an important social skill that keeps communications fun

Laughter is good for your health!

Laughter Yoga is not a substitute for proper medical consultation for physical, mental and psychological illnesses and may not be suitable for everyone. It is contra-indicated for people suffering from uncontrolled high blood pressure, heart disease, epilepsy, any kind of hernia, severe backache and major psychiatric disorders. This list is for guidance only and is not meant to be exhaustive. If in doubt, do not try it, and consult your trained medical professional for guidance. Anyone already undergoing physician-prescribed therapy should seek the advice of his or her doctor before reducing the dosage or stopping such treatment. Even a normal person experiencing discomfort while laughing, must discontinue immediately and seek expert medical help. Please use your common sense: no strain, no new pain.
From www.laughteryoga.us